Communication system



A TTORN'Y azz INVEN TOR.

C. J. FITCH COMMUNICATION SYSTEM F'lled Feb 9, 1955 Patented May 4, 1937lTED STATES COMIVIUNICATION SYSTEM Clyde J. Fitch, Jersey City, N. J.,assignor to International Business Machines Corporation, New York, N.Y., a corporation of New York Application February 9, 1935, Serial No.5,768

20 Claims.

'I'his invention relates to communication sys' tems and moreparticularly to printing telegraph systems and is suitably adaptable toboth radio and Wire network transmission.

Insofar as its fundamental features are concerned the methods hereindisclosed are applicable to any form of remotely controlled units andparticularly adaptable to be used in connection with tele-controlapparatus.

The present invention will be explained in conjunction with a singleimpulse synchronous transmission system, in which the differentcharacters to be transmitted and received are represented by singleimpulse signals which are definitely allocated during particular timedintervals.

This invention consists of a method and means for the transmission andreception of the translating signals, the system being characterized byutilizing bi-dlrectional controlling signals, in contra-distinction touni-directional signals. Heretofore the single impulse synchronoussystems employed aperiodic uni-directional impulses which involved theshifting of the character impulse along the axis of a timed scale, theposition of the impulse thereon determining the character to beselected. Therefore, in systems transmitting a variable number ofcharacterizations such as the representations of a typewriter keyboard,it is yimportant to use impulses of extremely short duration in order toinsure accuratel timing and allocation of the various impulses.Transmission speed liniitations are encountered owing to the fact thatthe rate of transmission is directly proportioned to the speed of thedistributing systems.

Increasing the speed of the* distributors also presents acutesynchronization diiliculties so that in remotely controlled printingtelegraph systems for example, the speed of the distributing systems.

must be operated at such rates that operation of the translating unitsmust be such as to conform to the speed limits obtainable, and'whichusually are normally lower than the average rate of operation of suchtranslating units, such as the conventional typewriters used in thepresent systems.

Reception of the impulses in the uni-directional lsignal systemsrequires special attention and equipment to properly allocate thesesignals on the distributing segments to prevent overlapping of impulsesthereon, in turn to prevent erroneousl operation of the recording ortranslating receiver units.

It is these disadvantages just mentioned that the present inventionproposes to overcome, which, broadly and briefly consists of thetransmission of bi-directional aperiodic, single, im-

pulses applied to synchronous controlling distributors, one method ofcontrol being the type using periodic uni-directional impulses formaintaining the synchronous condition thereof. This system permits thecontrolling segment length of the synchronous distributors to beincreased to twice the length used heretofore. It will be obvious tothose skilled in the art that the problem of allocating the receivedsignals is simpler in that the margin of operation is greatly icreased.Synchronizing of the rotary apparatus need not be as critical asherebefore, and as will be understood as the description progresses, therate of transmission of character impulses may be increasedproportionately.

It is therefore an object of the present invention to provide animproved printing telegraph system in which signalimpu1ses,.distinguished in respect to time, are utilized to select theprinting characters.

Another object of the present invention is the provision for the use ofbi-directional signal impulses in contradistinction tp uni-directionalimpulses to control the selecting of the characters to be transmittedand recorded.

Various other objects and advantages of the invention will be obviousfrom the following particular description of one form of mechanismembodying the invention or from an inspection of the accompanyingdrawing; and the invention also constitutes certain new and usefulfeatures of construction and combination of parts hereinafter set forthand claimed.

In thedrawing:

Fig. 1 shows a transverse sectional view of so much of one type oftele-printing machine as is necessary to illustrate a preferredembodiment of the invention.

Fig, 2 is a diagrammatic circuit diagram illustrating one form andembodiment of the invention.

Translating units For illustrative purposes, this invention is shown asembodying one well known form of translating unit and of the typedisclosed in the copending application Ser. No. 676,654, led June 20,1933, and hence requires only the following brief description.

Referring to the drawing and in particular to Fig. l, in the embodimentillustrated in the drawing, well known means are provided for actuatingthe type bars (not shown) by power operated devices comprising a powerdriven roller l0.

A cam ll is pivoted on one arm of a bell crank lever l2 pivoted in theframe, the other arm of which is operatively connected with one arm of abell crank lever i3 by means of link lf3. The other arm of lever i3 isconnected to the type bars (not shown) in a well known manner and fullydisclosed in the aforesaid application.

The lever l2 is actuated by the cam H when the latter engages the drivenroller l@ to be operated thereby.' The engagement of the cam il with thepower roller is controlled by means of the key lever il in a mannerwhich will now be described.

The cam il isresiliently engaged by a springpressed arm 2U which tendsto turn it into engagement with the power driven roller vor stop 2l on alever 22 pivoted on the bell crank i2 and normally arranged in the-pathof a lug on the cam. When the lever 22 swings to move its stop out ofthe path of the lug, the arm E@ swings the cam into engagement with thepower roller to be actuated thereby to swing the bell crank i2 toactuate its connected mechanism. The lever 22 has an arm 2t which isprovided with an oiset projection 25 at its end -which projectslaterally through an opening in the bell crank l2 and engages thebifurcated lower end 2S of an arm 2l of a key lever ll pivoted on thecommon rod 28.

It is obvious then that depression of a key lever H releases therevolubly mounted cam Ill to engage and be actuated by power roller Il@in turn operating bell crank l2 and its attached links to cause theassociated mechanism; such as the key bars and other operatingmechanisms, to be operated. Attached to the key lever ll is a connectinglink I9 extending to a solenoid l disposed beneath the keyboard, so thatupon energization of the said solenoid the connected key lever isdepressed to operate the connected mechanism in the same manner as justexplained.

In addition to actuating the several type bars and connected mechanisms,the revolubly mounted cams are adapted to make and break circuits whichmay be employed in the transmitting units the purpose of which will beunderstood as the description progresses. Upon release of the cam Il theensuing operation thereof causes the contact spring blade by virtue of'its attached cam follower roller 3l adapted to engage the cam during itspartial revolution, to be urged away from the power roller l0' to openthe contacts 32 and close the contacts 33. Since the cam turns exactlyone half of a revolution before being arrested, the spring blade 30returns to its normal position as shown in the drawing by virtue of itsown resiliency thereby restoring the contacts to their normal position,that is, contacts 32 closed and contacts 33 open.

It will be understood that the usual number of key bars and powerdevices with their associated mechanisms are provided, but only one ofthem is shown for the sake of clearness.

General description Referring now to Fig. 2, A represents a printingtelegraph unit which may be of the type described or any well known typehaving a series of character pivoted key bars l'l and adapted toinitiate a character impulse when one of the character keys isdepressed. The transmitting contacts may be positioned as explainedhereinbefore so as to open one set of contacts and close another by theoperating cams ll or the contacts may be positioned directly in contact'with' the keyboard l1 as shown in the figure.

acreage A separate contact 32a is associated with each individual keybar il and connected to segments of the distributor 36, a portion of thedevelopment of which is shown and further disclosure deemed unnecessarysince their use is well known in the art. Rotary arm 50 driven by anysuitable means such as a motor is adapted to engage the segments 35 inrathe-r'rapid succession to cause the transmission of the characterpulses. One method of setting' up the bi-directional character signalsis by the use of condensers, and as shown an individual condenser 38 isassociated with each key bar Il, the said condensers associated withcertain of the key bars are connected by a common conductor 39 to thenegative side of battery t0, while the condensers associated withcertain of the key bars are oonnected by a common conductor di to thepositive side of battery dll. It is to be noted that all the contacts32a, that is, the normally closed contacts, are associated with theconducting segments 35 of the distributor. Instead of associating eachcharacter key bar with an independent corresponding segment on thedistributor, two character key bars are connected to the samedistributor segment, such as the contacts 32a for the character key barsA and N are shown connected to segment 35-i, etc. In this manner, thenumber of segments 35 on the distributor 3@ may be reduced by half thenumber for the l same number of characterizations.

Disposed beneath or associated with the key bars ll and normally openare the contacts 33a connected to one side of the condensers 38. Theseare provided so that when a character key is depressed the condenser 38normally charged will be discharged by shorting the condenser throughcontact 33a.

supposing the key bar corresponding to character A was depressed todischarge its corresponding condenser, upon return of the key bar thecontact 32a. would be closed to connect the circuit from the negativeside of the battery through condenser 38, and the closed contact 32a toits corresponding segment 35i-l, so that when the rotating arm 5B withits conducting brushes d2 engages contact l, a circuit is completedthrough its other brush @3, solid and common conducting distributor ringM, conductor Q5 and the connected tank circuit consisting of the primarywinding of transformer d6 and condenser dl, the other side of said tankcircuit is connected to the common terminal of battery im. Therefore, itis seen that upon completion of this circuit just described, by therotating arm ll engaging the segment 35-l of the distributor, thecondenser just discharged by depression of the A character key is nowcharged negatively through the tank circuit and through the secondarywinding of transformer 46 and the connected transmitter the negativepulse is transmitted over the connected transmission network in the wellknown manner.

Assuming that the character N is to be transmitted, its correspondingcondenser 38 is discharged upon the depression of the key bar andthrough the connected circuit upon the return of the key bar throughcontact 32a and upon engagement of distributor segment 35--I by thebrush 62 of the rotary arm 50 the charging circuit is completed, in thisinstance, so that the condenser 38 is charged positively through thetank circuit and in this manner cause a positive pulse representation tobe'transmitted over the connected network.

Invthis manner it is seen that bi-directional pulses are originated torepresent individually different characterizations, and that each char.-acter segment of the distributor completes a circuit for both types ofpulses. It is evident therefore that the character signals are not onlydifferentiated by time or rather the transmission of the signals atparticular timed intervals but also that these signals aredifferentiated in character also. f

Of course, it must be understood that the method just described is oneform of originating the bi-directional impulses, the condenser dischargemethod could be used in the same manner, or simply the use of both polesof an E. M. F. source would be eiective to produce the character pulses.

In addition to the transmission of the aperiodic and bi-directionalcharacter signals a periodic uni-directional impulse is transmitted as asynchronizing signal and may be transmitted, for example, once eachrevolution of the rotary arm 50 so that upon engagement of distributorsegment 35A-20, a circuit is completed through conductor 48 to thenegative side of the battery d0 to transmit a corresponding Signal.

It was mentioned that the condensers 38 were assumed to be normallycharged, therefore, in order to insure correct operation of thetransmitting system upon starting, the normally closed switch 49included in the input circuit of the signal transmitter is opened untilthe individual condensers, which may have been discharged, are chargedby having all the distributor segments 35 engaged successively by therotary arm 50 `in a manner just described, and in this manner preventerroneous operation of the receiving system which will now be explained.

The broad principle of operation of single impulse systems of the typereferred to, as is Well known, depends upon the synchronous operation ofthe distributing or rotary units associated with the respectivetransmitting and receiving units. Such synchronizing units are old andwell known to those skilled in the art, and therefore a detaileddescription of this unit is not necessary. It is sulcient to mentionthat one type of synchronizing units utilizing periodic synchronizingimpulses such as, for example, a synchronizing impulse for eachrevolution of the transmiting rotary dlstributonvusually are arranged sothat if the rotary distributor at the receiver lags as compared to therotation of the transmitting distributor, the receiving rotary brush, byvirtue of such lagging engages a contact segment to energizeelectro-responsive devices by the transmitted synchronizing impulse tocause the rotary arm at the receiver to be advanced to such an extentduring its rotation so as to traverse the distributor segments in stepwith the transmitting distributor. If the receiving rotary arm isleading the transmitting arm, engagement of another con- I tact segmentcauses the electro-responsive devices to retard the rotation of therotary arm until synchronous operation is attained. For a completedescription of a synchronizing unit of the type just mentioned,reference may be made to the copending application Serial No. 684,362,filed August 9, 1933, patented Sept. 1, 1936, No. 2,053,- 091, which canbe embodied in this invention in the following manner:

'Ihe receiving distributor 5I is similar to the transmitting distributor36 and has disposed thereon the same number of segments 52 which areengaged in succession by a brush 53 attached A the distributor 5 l.

to rotary arm 54 driven by a suitable motor or device (not shown) sothat the arms 54 and 50 are rotated synchronously. As previouslymentioned, if the arm 54 lags in its rotation, and assuming uponreception of the periodic synchronizing impulse transmitted by thedistributor 36, the brush 53 engages the segment 52-2Ila, a circuit isthen completed through the synchronizer 55 and brush 56 and itsassociated conducting ring 51 to cause the synchronizing unit 55 toadvance the rotary arm 54 to rotate in synchronism with arm 50.Similarly, if the arm 54 is leading arm. 50, assume segment 20D isengaged by brush 53 upon reception of the synchronizing impulse, thesynchronizer is energized by the circuit completed through the saidsegment to retard the rotation of arm 54 to again rotate synchronouslywith arm 50. Unless otherwise specied in the description hereinafter, itis assumed that the arms 50 and 54 are operated in synchronism so thatthe like segments of the distributors 36 and 5I are engaged by theassociated brushes simultaneously.

A transformer 59 associated with the line cr radio receiver 60 which isadapted to receive theaperiodic bi-directional character pulses andperiodic synchronizing pulses transmitted by the transmitter 6|, has itsprimary winding connected to the output circuit of the said receiver.

The secondary winding of the said transformer has each of its terminalsconnected to the grids of thermionic tubes 62 and 63. The plates ofthese tubes are connected to series related primary windings oftransformers 64 and 65, the secondaries of which are connected toamplifiers 66 and 61 respectively which in turn are interconnected bycommon conductor 68 connected to the common conducting segment ring 51of The separate conductors 69 and 10 from the amplifiers are connectedto separate groups of the typewriter solenoids I8; for example,as'shown, the group of solenoids connected to character key bars for A,B, and C are commonly connected to amplifier 66, and the group ofsolenoids for characters N, O, and P are connected by conductor 10 toamplifier 61.

The other terminals of the solenoids I8 are connected to the individualsegments 52 lof the distributor 5i, each solenoid in a group as thesolenoids for characters A, B, and C are connected to segments 52-I. 2and 3 respectively; the terminals'of the solenoids I8 of the secondgroup N, O, and P are likewise connected to the separate segments 52-l,2 and 3, so that two character solenoids are connected to each segment,and the solenoids so connected represent the same characters as arerepresentedby tlie 'duo-connections to the transmitting distributorsegments from the contacts 32a associated with the character key barsl1.

A power supply, generally indicated at 12, supplies the elements oftubes 62 and 63 with the proper potentials, as indicated in the figureso that upon reception of a positive pulse representative of a charactertube 63 is energized thereby activating its connected output circuit,namely transformer 64 and amplier 66, similarly a negative pulse causesthe energization of tube 62 to activate its connected output circuit,transformer 65 and ampliiier 61. Normally, when no pulses are received,the grid elements of tubes 62 and 63 are biased so that an inappreciableamount of current ow exists in its separate output circuits so that thesolenoids I8 connected as described hereinbefore to the amplifiers 66and 61 are not energized when the rotary brush engages the varioussegments 52. Upon reception of a character pulse, one of the tubes 62and 63 is energized due to the grid swing caused by the incoming pulse,depending on the character of the incoming pulse. The operation of tubesconnected in the manner described is well known in the art and furtherdescription thereof is not deemed necessary.

Assuming that the pulse corresponding to character A is received, and asexplained this pulse is formed by the negative charging of condenser 38associated with the character A key bar l1, tube 62 is then energized toactivate the connected transformer 6i and amplifier 66, and since it isunderstood that brush 53 is engaging segment 52-1, a circuit iscompleted through solenoid i8 representing character A, by conductor 69,conductor 15, segment 52-l, brush 53, brush 56, common segment 51,conductor 16, to the return conductor 68 of amplit. 66, energizingcharacter solenoid representing A.

The energization of the said solenoid depresses the correspondinglylinked key bar I1 (Fig. 1) to release the revolubly mounted cam Il toengage and be actuated by the power roller HJ in turn operating theassociated bell crank t2 and its attached links and mechanism to operatethe type bar corresponding to character A and recording the saidcharacter accordingly.

Similarly, depression and release of the key bar l1 representingcharacter N of the teleprinter A causes the associated condenser i8 tobe charged positively through the tank circuit thereby causing thetransmitter 61 to send out a pulse representative of this character atits proper time in the cycle whenthe rotary arm 50 of distributor 36completes the said charging circuit through the conducting segment 35-I.Therefore, it is seen that for characters A and N, the pulserepresentations are characterized by the time of transmission during aparticular timed interval represented by the complete revolution of therotary arm 5D, the timed period in this predetermined intervalrepresenting by this characteristic two different representations.. Thesecond differentiating characteristic of the representations is thecharacter of the pulse transmitted during the particular timed intervalsselected, to control the final selection of the particular character atthe receiving or recording unit B.

Upon reception of the pulse representations of the character N by thereceiver 60, Aand upon energization of the connected transformer 59 bythe characteristic pulse, tube 63 is energized to activate transformer65 and the corresponding amplifier 61 to energize the circuit connectedto solenoid N through conductors 'I0 and 15 segment 52|, brushes 53 and56, common conducting segment 51, and conductors 16 and 68, whereby theenergized solenoid I8 depresses the key bar I1 to operate the charactertype bar and record the particular selected character.

While there has been shown and described and pointed out the fundamentalnovel features of the invention as applied to a single modification, itwill be understood that various omissions and substitutions and changesinthe form and details of the device illustrated and in its operationmay be made by those skilled in the art Without departing from thespirit of the invention. It is the intention therefore to be limitedonly as indicated by the scope of the following claims.

What is claimed is as follows: 1. In a communication system, means fortransmitting character impulses including means to initiate impulses ofequal timeduration but differing in character during a predeterminedtimed interval and means cooperating therewith to control the initiationof the impulses at differential times therein determining the selectedcharacters to be transmitted, and indicating means adapted to beoperated by the transmitted impulses in accordancewith the character andtime of reception of the said impulses to select the particularcharacter represented thereby.

2. In a communication system, means to initiate single impulses of equaltime duration but differentiated as to character to represent variouscharacterizations, means cooperating therewith to control the initiationof the said impulses at differential times during predetermined timeintervals determining the selection of particular characterizations andmeans to transmit the impulses diierentiated as to time and characterrepresenting the selected characterization.

3. In a communication system, means to transmit character impulses ofequal time duration having different characteristics including cyclical-1y operable means for initiating impulses at differential times duringpredetermined timed intervals representing different characters, andcontrolling means cooperating therewith to select the character of andtimed intervals at which the impulses are initiated in accordance withthe various characters to be transmitted, and means adapted to beoperated by the transmitted impulses and in accordance with theirselection.

4. In a communication system, 'means for transmitting character impulsesof equal time duration having different characteristics includingcyclically operable mechanism for initiating `current impulses atdifferential times during predetermined timed intervals to representdifferent characters, each by a single differentially timed impulse andcontrolling means cooperating therewith to select the character of andtimes at which the single character impulses are initiated in accordancewith the diierent characters to be transmitted, and means adapted to beoperated by the transmitted impulses and in accordance with theirselection.

5. In a communication system, means for' transmitting aperiodic signalimpulses of equal time duration but of unlike character representingvarious characterizations, means for transmitting periodic impulses oflike character, means U.

for receiving the said impulses including means controlled by the saidperiodic impulses of like character and means controlled by; theaperiodic sent different characterizations, each by a single selectedimpulse, means for transmitting periodic impulses of like character, andmeans for receiving the said impulses including means controlled by thesaid periodic impulses of like character and means controlled by theaperiodic impulses of unlike character.

8. In a communication system, means for transmitting bi-directionalcharacter impulses of equal time duration to represent differentcharacterizations, each by a single selected impulse, means fortransmitting uni-directional synchronizing impulses, and means forreceiving the said impulses including means controlled by theuni-directional synchronizing impulses and means controlled by thebi-directional character impulses.

9..In a communication system, a plurality of stations, each of saidstations having a contnuously operated control device, the operation ofeach of said control devices being in timed relation with that of theother, means to select impulses of unlike character to representdifferent characterizations, each by a single selected impulse, meanswhereby the said selected impulses are transmitted from one of saidstations at instants of time governed by the operation of its saidcontrol device, and indicating means at another of said stationsresponsive to the said impulses, said indicating means being governed bythe control device associated therewith.

10. In a communication system comprising a plurality of stations, eachof said stations having a continuously operated control device, theoperation of each of said control devices being in timed relation withthat of the other, means to select bi-directional impulses to representdiEerent characterizations, each by a single selected impulse, meanswhereby the said selected impulses are transmitted from one of saidstations at instants of time governed by the operation of its saidcontrol device, and indicating means at another of said stationsresponsive to the said impulses, said indicating means being governed bythe control device associated therewith.

11. A communication system, in combination, a signal impulsetransmitter, translating units comprising signal transmittinginstrumentalities, control devices comprising a plurality of controllingmembers, a plurality of said instrumentalities associated with each ofthe said controlling members, energy supply means associated with thesaid instrumentalities whereby the operation of one thereof selects thecharacter of the signal impulse to be transmitted, and means included inythe said control devices governing the transmission of said selectedsignal impulses.

12. A communication system comprising means to transmit signal impulses,including 'a translating unit comprising signal transmittinginstrumentalities, a. control device comprising a plurality ofcontrolling members, a plurality of said instrumentalities associatedwith each of the said controlling members, energy supply meansassociated with the said instrumentalities whereby the operation of onethereof vselects the character of the signal 'impulse to be transmitted,and means included in the said control device governing the transmissionof said selected signal impulses, means to receive the signal impulses,a second translating unit comprising a-plurality of signal receivinginstrumentalities, a control device comprising a plurality ofcontrolling memincluded in the last mentioned control device governingthe operation of the said selected receiving instrumentality.

13. In a communication system, a translating unit comprising a pluralityof operable instrumentalities, means to select signal impulses differingin character upon operation of the selected instrumentalities, means tostore the selected signal impulse, and a control device including meansgoverning the transmission of the said selected impulse stored by thesaid storage means.

14. In -a communication system comprising means to transmit signalimpulses of different character,'a translating unit comprising aplurality of operable instrumentalities, circuits con- -trolled by saidinstrumentalities, storage devices included in said circuits, wherebythe operation of the selected instrumentalities condition the saidcircuits and storage devices for the selection of the signal impulsesunlike in character, and a control device including means governing thetransmission of the selected impulses.

l5. In a communication system comprising means to transmit signalimpulses of unlike character, a translating unit comprising a pluralityof operable instrumentalities, circuits controlled by saidinstrumentalities, electrostatic means ineluded in said circuits,whereby the operation of the selected instrumentalities condition thesaid circuits and electrostatic means for the selection of single signalimpulses unlike in character, each impulse indicative of definiterepresentation, and a. control device including means governing thetransmission of the selected single impulses.

16. In a communication system, means to receive signal impulses ofunlike character, a control device comprising a plurality of controllingmembers, a translating unit comprising a plurality of signal receivinginstrumentalities, of

Awhich a plurality are associated with each of the laccordance with thecharacter of the signal impulse received.

17. In a communication system, means to receive signal impulses ofunlike character comprising a plurality of electrostatic devices ofwhich a predetermined number are responsive to signal impulses ofpredetermined character and the other electrostatic devices responsiveto impulses of different characters, and indicating means capable ofperforming independent operations, which are controlled by the characterof the impulses received.

18. In a communication system, means to receive signal impulses ofunlike character, a translating unit comprising a plurality of signalreceiving instrumentalities, a plurality of electromagnetic devicesassociated with said instrumentalities, a control device comprising aplurality of control members to each one of which are connected two ofthe said electromagnetic devices, and means included in the said controldevice governing the energization of the electromagnetic devicesselected in accordance with the character of the signal impulsesreceived.

19. A communication system comprising means to transmit signal impulses,including a sending unit comprising a plurality of operable keyinstrumentalities, a circuit control device comprising a, plurality ofcontact members and a ro-f tatable contact arm adapted to engage thesaid contact members successively, a plurality of circuits connecting apredetermined group of said 6 acreage key instrumentalities to each ofthe said contact members, energy supply means associated with the saidinstrumentalities whereby the operation of one selects the character ofthe signal impulse to be transmitted, the time of transmissioncontrolled by the said rotary contact arm, means to receive the signalimpulses, a receiving unit comprising a plurality of printing controlinstrumentalities, a circuit control device com- 10 prising a pluralityof contact members and a rotatable contact arm adapted to engage thelast mentioned contact members successively, a plurality of circuits toconnect a predetermined group of the said printing controlinstrumentalities 15 to each of said last mentioned contact members,

and means associated with the said receiving means to select one of thesaid group o printthe said circuit and adapted to store the selectedimpulse accordingly, and a circuit control device governing thetransmission of the said selected impulse stored by the said storingmeans.

l CLYDE J. FITCH.

